Tank floor flatness

[Nick Miles]

Good Day Gents

 

 

Could someone offer their opinion on a storage tank being constructed to API 650. There is quite severe distortion around the annular plates peaking at approximately 50mm from grade level. This is obviously from poor construction and welding sequence. API 650 clause 7.2.2.1 states tank floor must have “as nearly as possible a plane surface”.

Contractor is stating that as there are no specific tolerances in the code then this situation cannot be rejected. I have concerns about stresses being placed on welds when tank is filled and kindly request guidance from anyone who has specific experience in this.

 

Kind regards

 

Nick Miles

[Lassaad]

Dear Nick,

If your contractor has followed a right weld sequences mapping (short seams, then long, with opposite directions and from thé centre to thé sides) plus à good clumpsing, there's no worry about stress within plates joints.

Where for the annuler plates, you should use thé needed shims and proceed by grouting fill after overall welding completion.

My questions are:

Is there a bituminous/oily sans layer underneath the bottom plates?

If yes, was this bituminous layer survey done with respect to the API650?

If you share photos It would be grate.

Sent from my iPad

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[c sridhar]

The distortion in the bottom plate welding could be  due to wrong welding procedure  / sequence.
API 650 asks for a flat plane surface and not  mentioning of tolerances can not be taken as an excuse.
Enclosing  the  weld sequence details for your study and consideration.

Sridhar.

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From: Nick Miles <Ni...@ritc.co.za>
To: "material...@googlegroups.com" <material...@googlegroups.com>
Sent: Friday, 13 September 2013 2:25 PM
Subject: [MW:18643] Tank floor flatness